As sea ice disappears, the emergence of open ocean deep convection in the Arctic has been suggested. Here, using 36 state-of-the-art climate models and up to 50 ensemble members per model, we show that Arctic deep convection is rare even under the strongest warming scenario. Only 5 models have somewhat permanent convection by 2100, while 11 have had convection by the middle of the run. For all, the deepest mixed layers are in the Eurasian basin, by St Anna Trough. When the models convect, that region undergoes a salinification and increasing wind speeds; it is freshening otherwise. We discuss the causality and potential reasons for the opposite trends. Given the model’s different parameterisations, and given that the ensemble members that convect the deepest, most often, are those with the strongest sensitivity, we conclude that differences in deep convection are most likely linked to the model formulation.
Sea ice production within polynyas, an outcome of the atmosphere - ice - ocean interaction, is a major source of dense water and hence key to the global overturning circulation, but is poorly quantified over open-ocean polynyas. Using the two recent extensive open-ocean polynyas within the wider Maud Rise region of the Weddell Sea in 2016 and 2017, we here explore the surface ice energy budget and estimate their ice production based on satellite retrievals, in-situ hydrographic observations, and the Japanese 55-year Reanalysis (JRA55). We find that the oceanic heat flux amounts to 36.1 and 30.7 W m-2 within the 2016 and 2017 polynyas, respectively. We find that the 2017 open-ocean polynya produced nearly 200 km3 of new sea ice, which is comparable to the production in the largest Antarctic coastal polynyas. Finally, we find that ice production is highly correlated with the 2 m air temperature and wind speed, which affect the turbulent fluxes. It is also highly sensitive to uncertainties in the atmospheric air temperature and mixed layer depth, which urgently need to be better monitored at high latitudes.